By-pass engine having a single, thrust diverter valve mechanism for a v/stol aircraft

ABSTRACT

A thrust diverter valve assembly for a bypass engine including a plurality of flap elements pivotally mounted for alternate adjustments between a first position diverting bypass flow to a straight-through passage for augmenting the main thrust being developed, and a second position diverting the bypass flow to a vertical-takeoff-and-landing mode of operation. Hinged sections provide sealing between adjacent flap elements, and serve as flow-straightening vanes when the flap elements have been adjusted to their vertical flight mode.

United States Patent [1 1 Stevens [111 3,769,797 1 Nov. 6, 1973 {2;Filed:

[21] App1.No.:193,436

[54] BY-PASS ENGINE HAVING A SINGLE,

TIIRUST DIVERTER VALVE MECHANISM FOR A'V/STOL AIRCRAFT [7'5] inventoriEmrsbifwlstviifluffam, N17.

[73] Assignee: The United States of America as represented by theSecretary of the Air Force, Washington, DC.

oct. 28, 1971 [52] US. Cl 60/226 R, 60/229, 239/2652) [51] Int. Cl. F02k1/20, F02k 3/04 [58] Field of Search 60/226 R, 229;

[56] I I 1 References Cited UNITED STATES PATENTS 2/1965 Sandre 60/22910/1966 Marchant 60/226 R 3/1971 Mortlock 239/265.29

3,577,736 5/1971 Stevens 60/226 R 3,611,725 10/1971 Short 239/265.29

FOREIGN PATENTS OR APPLICATIONS Primary Examiner-Doug1as HartAttorney-Harry A. Herbert, Jr. et a1.

[57] ABSTRACT A thrust diverter valve assembly for a bypass engineincluding a plurality of f1ap elements pivotally mounted for alternateadjustments between a first position d1 verting bypass flow to astraight-through passage for augmenting the main thrust being developed,and a sec- ,ond position diverting the bypass flow to averticaltakeoff-and-landing mode of operation. Hinged sections providesea11ng between adjiacent'flap elements, and serve as flow-straighteningvanes when the flap eleme'nts have been adjusted to their verticalflight mode.

'1" CTiiiiiIi matting 'Fi'g IEi-Es" 7/1961 France. ..60/226 R PatentedNov. 6, 1973 3,769,797

AIRCRAFT BACKGROUND THE INVENTION This invention relates to the use ofthe bypass engine principally for VTOL aircraft.

In the continued development of jet aircraft that have previouslyrequired ever-increasing take-off and landing speeds and thereforerunway distances, there has been a considerable effort in progress todesign aircraft with lower and lower minimum takeoff and landing speedsin order to substantially decrease the take-off and landing arearequired. To this end, both the VTOL,

vertical-takeoff-and-landing aircraft and STOL, shorttakeoff-and'landingaircraft,'and the necessary power plants therefor, have been underdevelopment for many years. Many of the VTOL. aircraft are equipped withhigh-lift devices and are therefore also designed to perform shorttakeoffs and landings. These aircraft are usually referred to as V/STOLaircraft. Concurrent with the development of such VTOL and/or V/STOLaircraft has been the development of improved types of variouspropulsion systems, such as the rotor, propeller, ducted fan, andturbojet engines. The present invention is concerned with .an improvedmeans for diverting the thrust of a-by pass engine, which, of course, isa modified turbojet engine, from the horizontal or forward flight modeof operation to the vertical flight mode of operation. The by-passengine is selected for application of the present improvement, to befurther explained, because the pure turbojet, as is well-known, suffersfrom thedisadvantage of relatively low propulsive efficiency at lowspeeds, due to its jet exhaust velocity being far greater than that ofthe aircraft itself. Thus, with the VTOL or V/STOL aircraft, vertical oralmost vertical takeoffs, for example, are possible until a safe heighthas been reached that is sufficient to clear any obstacles, whereupontransition to horizontal or forward thrust occurs. To provide therequired greater propulsive efficiency at low speed in amore effectivemanner than other systems heretoforproposed, the present applicantdeveloped the thrust diverter means described and claim'ed in acopending patent application, Ser. No. 77,776, filed Oct'. 5, 1970, andnow 11.8.

Pat. No. 3,660,981, issued on May 9,, 1972 on an inven tion entitled"The V/STOL Aircraft. In the latter application, a source of compressedair is utilized to act 1 against, and thereby control the movement of asecondary air flow around the main turbojet engine portion either to thehorizontal, thrust-augmentation configuration, or to the vertical flightmode. The single, thrust diverter valve mechanism of the presentinvention constitutes a further novel development of the use of theby-pass engine in VTOLaircraft, as will appear selfevident-he'reinafterin the following summary and detailed description thereof.

SUMMARY OF THE INVENTION The present invention consists in a by-passengine incorporating a single, thrust diverter valve assembly having aplurality of flap elements hingedly mounted with the bypass portion ofthe engine for pivotal movement in one of two positions respectivelyblocking bypass flow from a bypass annulus formed in the engine calflight modes of operation: Hinged sections are incorporated betweenadjacent flap elements to maintain a seal therebetween, and to serve asflow-straightening vanes during the vertical flight mode of operation.

Certain objects and advantages of the invention will become readilyapparent from the following disclosure thereof, taken in connection withthe accompanying drawings, in which: i

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional andschematic view, illustrating the overall configuration of one form of bypass fanturbojet engine to which the improvement of the presentinvention may be applied;

FIG. 2 is a broken away, partly schematic, and crosssectional view,taken about on line 2-2 of FIG. 1, showing certain details of theimproved valve assembly of the invention; and

FIGS. 3a, b and c represent relatively enlarged schematic andbroken-awayfragmentary views, illustrating respectively the forward, transition andvertical flight configurations of the improved and yet simplified hingedsections formed between adjacent flap segments comprising the novelvalve assembly of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring particularly to FIG. 1of the-drawings, a by? pass fan-type of turbojet engine to which theimprovement of the present invention may be applied is indicatedgenerally at 10 as including, in part, an inner shell 11, an outer.shell 12 forming a bypass annulus therebetween, as is indicated at 13,in which bypass annulus 13 may be positioned the diffuser I4. I-Iousedor enclosed within the inner shell 11 is the pure turbojetengineportionof the present engine which consists principally of acompressor section comprising .the main, compressor-support member at 15and a plurality of alternately arranged stator and rotor blade elements,indicated generally at 16, a turbine-at 17, a main, rotatable supportingshaft, indicated at 18 as being disposed iniinterconnected relationbetween said compressor-support merriberlS and said turbine 17, a pairof combustion chambers at 1 9 and 20, and any exhaust or tail pipesectionat2l.

' Mounted for simultaneous rotation with, and immediately forward orupstream of the compressor-support member 15, on the stub shaft element22, isthe fan, indicated in schematic form at 23. As clearly depicted inthe aforementioned FIG. 1, the peripheral portions of the fan 23 extendin an overlapping relation to the inlet of the bypass annulus 13, sothat rotation of the fan 23 results in the formation of both aprimarycompressed air flow through-the compressor section 15, 16 and theturbine 17, and a bypass or secondary air flow through the bypassannulus 13 for entry into one or the other of two annular passages orchambers to be hereinafter further described. The primary air flowthrough the inlet of the compressor section 15, 16, of course, isdirected downstream to the combustion chambers 19 and 20 where it ismixed with fuel and ignited in a wellknown manner, and thereafter thehot combustible products thereof are exhausted against, and causerotainto one or the other of two bypass passages or chambersrespectively representing the horizontal and vertition of, the blades ofthe turbine 17. This rotation of the turbine 17 naturally effects arotation of the compressor section 15, 16 inthe usual manner ofoperation of ,the pure turbojet engine. In this regard, it is notedthat,

, Y 3 although in the schematic view of FIG. 1, only one compressorsection has been illustrated,in practice, there may be both low and highpressure-compressor sections incorporated therewithin. Also, in thepresent arrangement, the single turbine at 17 is depicted as providingthe operating means for both the compressor section 15, 16 and the fan23. However, a second turbine (not shown) would generally be used forthis purpose without departing from the true spirit or scope of theinvention. In any event, the hot combustible products formed by theprimary air flow would be exhausted out the tail pipe section 21, afterthe extraction of a portion of its energy to drive the compressorsection 15, 16 and, in this case, the fan 23, to thereby provide theprincipal thrust for forward flight.

The'bypass or secondary, cold and compressed air flow being urgedthrough the bypass annulus 13 by the fan 23 may be alternately directedinto one or the other of two bypass or secondary flow paths by the noveland yet greatly simplified single, thrust diverter valve assembly of thepresent invention'to thereby either augment the main thrust beingproduced by the exhaustion of combustible products out the tail pipesection 21 for forward'flight, or to change the secondary air flow tothe vertical flight mode of operation. For this purpose, for the forwardor horizontal flight mode, the bypass annulus 13 communicates with afirst, bypass or secondary air flow path formed by a first, substantialaxially-aligned, annular passage or relatively elongated chamber at 24that is also open at its rear end and in which the direction of flow isindicated by the broken arrows at 25. For the vertical flight mode, saidbypass annulus 13 also communicates with a second, bypass or secondaryair flow path formed by a second, annular passage or relatively enlargedchamber, indicated at 26, that is disposed further outwardly of, and inconcentric relation to, the said first, annular passage or elongatedchamber 24 and incorporates an opening, or what may be called thevertical-take-off and landing (VTOL) outlet, indicated generally at 28,that is naturally oriented in a vertically-downward direction to therebydirect the entire bypass or secondary air flow in the said passage orenlarged chamber 26 in the'direc- .tion of the solid arrows at 27 forthe vertical take offand-landing flight condition.

To alternately direct the bypass or secondary air flow entering thebypass annulus 13 into either of the previously-referred to forward orvertical flight modes of operation, the improved single, thrust divertervalve assembly of the present invention may be installed in the bypassfan-turbojet engine 10 between the inner end and outer shells l1 and 12theroef, and operate in the novel and yet simplified manner to behereinafter described. Said diverter valve assembly, which is indicatedgenerally at 29 in FIG. 2, may consist of a plurality of separate flapsegments, preferably consisting of a total of twelve and arranged ininterconnected sets of three each, such as is indicated, for example, at30, 31 and 32 in the aforementioned FIG. 2. The said flap segments maybe hingedly mounted for pivotal movement relative to a main supportmeans, seen at 24a in FIG. 1, which support means 24a may comprise oneof the wall surfaces of the passage or chamber 24. With thisarrangement, a single actuator, as at 33 in FIG. 1, may be used tooperate or pivot each set of three flap segments, as at 30, 31 and 32,to either of the two operative positions, depicted in solid and dashedlines in both FIGS. 1 and 2. In the aforesaid FIG. 1, the middle flapsegment of the above-described set of three is indicated at thereference numeral 31. Said actuator 33 is shown applied to the said flapsegment 31 at the point of application indicated at 34 in FIG. 2. Thecenterline or hinge axis of the entire group of flap segments isdepicted schematically at 35.

Again referring to FIG. 2, it is clearly seen that the flap segments, asat 30, 31 and 32, of the present single, thrust diverter valve assembly29 have each been constructed with a tapered configuration, formed by agreater width at the hinge axis 35, for the specific purpose ofaccommodating the reduced area available to the said flap segments whenthey have been pivoted to their solid line position, seen in FIG. 2, forexample. In this connection, the unique thrust diverter valve assembly29 comprising the improvement of the present invention furtherincorporates novel hinged sections at, and interconnected with, theedges of adjacent flap segments, as at 30, 31 and 32, the importantparts of which hinged sections being illustrated in the fragmentaryviews of FIGS. 3a, b and c. In FIG. 3a, for example, the hinged sectionthereof is indicated generally at 36 as consisting of a pair ofhinge-plate elements at 37 and 38 that are respectively hinged to eachother at 39 and are further hinged to the flap segments, for example,those indicated at 31 and 32 in FIG. 2, by means of the hinge meansindicated generally, schematically and respectively at the referencenumreals 40 and 41. With the aforesaid hinged sections, as at 36, asealed relation between the various flap segments, as at 30, 31 and 32,is maintained in all positions of the said flap segments. Moreover, saidhinged sections, as at 36, serve as flowstraightening vanes inthevertical takeoff-and-landing mode of operation to be hereinafter furtherdescribed. In this connection, FIGS. 3a, b and c respectively illustratethe positions of the said hinged sections 36 during the forward flightmode, the transition period, and the vertical-takeoff-and-landing (VTOL)mode of operation of the present invention. 1

With the foregoingsystem, the flap segments 29 comprising the inventivesingle, thrust diverter valve assembly 29 may be easily adjusted toeither of thepreviously-mentioned two operative positions either toaugment the main thrust being developed for forward flight, oralternatively, to achieve the desired vertical flight mode. For theaforesaid thrust-augmentation mode of flight operation or, in otherwords, for the forward flight condition, the plurality of flap segments,as for example, the previously-noted flap segments 30, 31 and 32, wouldbe adjusted, as by means of their pivoting about the pivot or hinge axis35 of the previously-noted support means 24a, through the actuation ofthe actuator, such as is indicated at 33 in FIG. 1, to the'dotted lineposition, indicated at 31a for the flap segment 31 in FIG. 1. Thisaction results in the closing of communication between, and thereforethe flow of bypass or secondary air from the bypass annulus 13 into thepreviously-described second, annular passage or relatively enlargedchamber 26 of the vertical flight mode of operation. Simultaneouslytherewith, the pivoting of the diverter valve assembly-flap segments,such as at 31, to the dotted line position of 31a, results in theconcurrent opening of communication between, and the formation of, astraight-through flow path comprising the said bypass annulus 13 and thefirst, substantially axially aligned, relatively elongated passage orchamher 24 (Note FIG. 1) for thereby diverting and exhausting the entirebypass or secondary air flow directly out the open rear or bypass nozzleend of said annular passage 24 to thus augment the main forward thrustof the engine. I

When the vertical flight mode (VTOL) is desired, the flap segmentscomprising the present valve assembly, as at 30, 31 and 32, may bepivoted to the solid line position, as for example that depicted for theflap segment 31, whereupon the flow of bypass or secondary air to thefirst, relatively elongated passage or chamber 24 (Note FIG. 1) isblocked, and the said flow is thereby simultaneously diverted to thenow-opened communication between the said by-pass annulus 13 and thesecond, relatively enlarged, outer chamber at 26 which is, in turn, inopen communication with the VTOL system outlet opening at 28, forthereby directing the bypass or secondary air flow in a verticallydownward direction and thus achieve vertical or substantially verticalflight in either takeoff or landing configuration.

I claim! 1. A bypass fan engine incorporating a main, forwardthrust-producing, turbojet portion including compressor, turbine,combustion and main exhaust sections for acting on, and producing themain, forward thrust of the engine from the hot combustible products ofthe mixture of fuel and a primary air flow therethrough; and a combined,forward thrust-augmentation and vertical-takeoff-and-landing producingportion including a bypass annulus arranged in concentric andsurrounding relation to, and outwardly of and between the casing of thesaid turbojet engine-portion constituting an inner shell element, and anouter shell element spaced from said inner shell element; said by-passannulus further having an upstream or inlet end portion open to the mainair inlet of the engine, afan for directing, pressurizing and convertinga portion of the main engine-incoming air into a' by-pass or secondaryair flow initially entering the said upstream or inlet end portion ofsaid by-pass annulus, and a combined wall and valve mechanism-supportmember intermediatelydisposed between the said inner and outer shellelements comprising said by-pass annulus, and oriented in surroundingrelation to the said turbojet engineportion, said wall and supportmemberbeing further arranged to divide said bypass annulus into bothsubstantially horizontally and vertically-oriented flow pathsrespectively comprised of a first, relatively narrow and horizontal,bypass or secondary air flow passage means disposed in immediateconcentric relation to the casing/inner shell element of said turbojetengine-portion and 'having a first, relatively small inlet portion inopen communication with, and receiving the bypass or secondary air flowfrom, the upstream or inlet end portion of said bypass, annulus, and afirst, horizontally-oriented exhaust means forming a first,substantially straight-through and relatively narrow flow path-passagewith the said upstream or inlet end portion of said by-pass annulus forthereby exhausting the bypass or secondary air flow entering the saidbypass annulus and said substantially straight-through flow path-passagein a rearward direction to thus substantially augment the main, forwardthrust being produced by the turbojet engine-portion; and a second,separate, relatively enlarged and substantially vertically-oriented,bypass or secondary air flow path-passage means disposed furtheroutwardly of, and between the said combined wall and valvemechanism-support member forming the said first-named passage means andthe said by-pass annulus-outer shell element, said relatively enlargedand substantially verticallyoriented, flow path-passage means furtherhaving a second, relatively enlarged, inlet portion in opencommunication with, and receiving the bypass or secondary air flow from,the upstream or inlet end portion of said bypass annulus at an anglerelative to, and further outwardly of, the said first, inlet portion ofsaid first-nam ed passage means, and a second, downwardly-oriented,exhaust means forming a second, substantially vertical,

flow path-passage with the said upstream or inlet end portion of saidbypass annulus for thereby exhausting the bypass or secondary air flowentering said bypass annulus and said second, vertically-oriented flowpathpassage in a vertically-downward direction representing thevertical-takeoff-and-landing mode of engine operation; and thrustdiverter valve means for alternately directing the bypass or secondaryair flow entering said bypass annulus into one or the other of saidfirst and second-named, bypass or secondary air flow-passages to therebyeither augment the main, forward thrust being produced in the engine, orto establish the verticaltakeoff-and-landing configuration thereof; saidthrust diverter valve means comprising; a plurality of separate flapsegments interconnected in sealed relation to each other, in apredetermined number of sets, by a series of flap sections pivotallymounted in alternate relation between successive flap segments, andbeing further collectively hinged, for pivotal movement, incircumferential relation to, and around the upstream end of the saidcombined wall and valve mechanism-support member; said thrust divertervalve means further comprising power means respectively interconnectedwith each of the said predetermined number of flap segment-sets forthereby pivoting said plurality of flap segments to either of twoalternate positions respectively blocking either the first-named,forward thrust-augmenting, straightthrough flow path-passage, or thesecondnamed, substantially vertically-oriented, flow pathpassage; saidflap segments further having a tapered configuration with the greaterwidth at the hinge axis for thereby positively accommodating for thereduced area available when the said flapsegments have pivoted to thesaid first-named passage in blocking position immediately upstream ofthe first, relatively small inlet portion of the said relatively narrowand horizontal, bypass or secondary air flow-passage means comprisingthe forward thrust-augmentation mode of engine operation.

1. A bypass fan engine incorporating a main, forward thrustproducing,turbojet portion including compressor, turbine, combustion and mainexhaust sections for acting on, and producing the main, forward thrustof the engine from the hot combustible products of the mixture of fueland a primary air flow therethrough; and a combined, forwardthrust-augmentation and vertical-takeoff-and-landing producing portionincluding a bypass annulus arranged in concentric and surroundingrelation to, and outwardly of and between the casing of the saidturbojet engineportion constituting an inner shell element, and an outershell element spaced from said inner shell element; said by-pass annulusfurther having an upstream or inlet end portion open to the main airinlet of the engine, a fan for directing, pressurizing and converting aportion of the main engine-incoming air into a by-pass or secondary airflow initially entering the said upstream or inlet end portion of saidby-pass annulus, and a combined wall and valve mechanism-support memberintermediatelydisposed between the said inner and outer shell elementscomprising said by-pass annulus, and oriented in surrounding relation tothe said turbojet engine-portion, said wall and support member beingfurther arranged to divide said bypass annulus into both substantiallyhorizontally and verticallyoriented flow paths respectively comprised ofa first, relatively narrow and horizontal, bypass or secondary airflow-passage means disposed in immediate concentric relation to thecasing/inner shell element of said turbojet engine-portion and having afirst, relatively small inlet portion in open communication with, andreceiving the bypass or secondary air flow from, the upstream or inletend portion of said bypass annulus, and a first, horizontally-orientedexhaust means forming a first, substantially straight-through andrelatively narrow flow pathpassage with the said upstream or inlet endportion of said bypass annulus for thereby exhausting the bypass orsecondary air flow entering the said bypass annulus and saidsubstantially straight-through flow path-passage in a rearward directionto thus substantially augment the main, forward thrust being produced bythe turbojet engine-portion; and a second, separate, relatively enlargedand substantially vertically-oriented, bypass or secondary air flowpath-passage means disposed further outwardly of, and between the saidcombined wall and valve mechanism-support member forming the saidfirst-named passage means and the said by-pass annulus-outer shellelement, said relatively enlarged and substantially vertically-oriented,flow path-passage means further having a second, relatively enlarged,inlet portion in open communication with, and receiving the bypass orsecondary air flow from, the upstream or inlet end portion of saidbypass annulus at an angle relative to, and further outwardly of, thesaid first, inlet portion of said first-named passage means, and asecond, downwardly-oriented, exhaust means forming a second,substantially vertical, flow path-passage with the said upstream orinlet end portion of said bypass annulus for thereby exhausting thebypass or secondary air flow entering said bypass annulus and saidsecond, verticallyoriented flow path-passage in a vertically-downwarddirection representing the vertical-takeoff-and-landing mode of engineoperation; and thrust diverter valve means for alternately directing thebypass or secondary air flow entering said bypass annulus into one orthe other of said first and second-named, bypass or secondary airflow-passages to thereby either augment the main, forward thrust beingproduced in the engine, or to establish the vertical-takeoff-and-landingconfiguration thereof; said thrust divertEr valve means comprising; aplurality of separate flap segments interconnected in sealed relation toeach other, in a predetermined number of sets, by a series of flapsections pivotally mounted in alternate relation between successive flapsegments, and being further collectively hinged, for pivotal movement,in circumferential relation to, and around the upstream end of the saidcombined wall and valve mechanismsupport member; said thrust divertervalve means further comprising power means respectively interconnectedwith each of the said predetermined number of flap segment-sets forthereby pivoting said plurality of flap segments to either of twoalternate positions respectively blocking either the first-named,forward thrust-augmenting, straight-through flow path-passage, or thesecond-named, substantially vertically-oriented, flow pathpassage; saidflap segments further having a tapered configuration with the greaterwidth at the hinge axis for thereby positively accommodating for thereduced area available when the said flap segments have pivoted to thesaid first-named passage in blocking position immediately upstream ofthe first, relatively small inlet portion of the said relatively narrowand horizontal, bypass or secondary air flow-passage means comprisingthe forward thrust-augmentation mode of engine operation.